Fabric dyeing method

Abstract

This application provides a fabric dyeing method, belonging to the technical field of reactive dye dyeing of textiles. After fully soaking a to-be-treated fabric containing ammonium groups in solvent A, microwave heating is performed for water-free modification pretreatment to obtain a pretreated fabric. The pretreated fabric is then immersed in a dye liquor for dyeing to obtain a dyed fabric. Solvent A and solvent B are both composed of a hydrogen bond donor and a hydrogen bond acceptor. This method can be used to dye cotton, linen, wool, and silk fabrics, achieving advantages such as high dye uptake, high color accuracy, and excellent color fastness.

Description

Technical Field

[0001] The present application relates to a fabric dyeing method, belonging to the technical field of reactive dye dyeing of textiles. Background Art

[0002] Commonly used dyes for fiber or fabric dyeing include reactive dyes, vat dyes, and disperse dyes, with reactive dyes being the most widely used. In industrial processes, reactive dyes are widely used for silk dyeing due to their relative ease of application, low cost, wide color gamut, and high wet fastness. However, due to the decomposition and ionization of reactive dyes in water, their utilization rate is only 60-65%. To increase the dye uptake, large amounts of electrolytes are added during the reactive dyeing process to address the repulsive charges between the fiber and the reactive dye caused by this decomposition and ionization. However, these added electrolytes neither consume nor decompose, and their presence in the dye liquor results in the generation of large amounts of electrolyte-containing wastewater during the dyeing process. Residual dye and electrolytes in this wastewater not only pose serious environmental risks in living organisms but also cannot be directly reused, contributing to the significant waste of water resources in the printing and dyeing process.

[0003] In response to the above-mentioned problems in the dyeing process, most companies focus on how to purify wastewater, or solve the environmental problems of water resource waste and direct discharge of wastewater by converting wastewater into other uses. How to solve wastewater pollution and increased production costs by improving dye utilization is an urgent problem that needs to be solved in this field, but no reports have been seen yet. Summary of the Invention

[0004] In view of this, the present application provides a fabric dyeing method, which achieves fabric modification pretreatment by means of pretreatment, thereby improving the dye affinity and the adsorption capacity of the fiber to the dye molecules, thereby achieving an increase in the dyeing rate.

[0005] Specifically, this application is implemented through the following solutions:

[0006] A fabric dyeing method comprises the following steps:

[0007] (1) soaking the ammonium-containing fabric to be treated in solvent A, stirring to ensure full contact, and then performing anhydrous modification pretreatment by microwave heating. After the reaction is completed, separating to obtain the pretreated fabric; the solvent A is composed of a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor is any one of lactic acid, urea, citric acid, and fructose, the hydrogen bond acceptor contains a carboxyl group that reacts with the ammonium group in an amidation reaction, and the mass ratio of the hydrogen bond donor to the hydrogen bond acceptor is 3 to 4:1;

[0008] (2) The pretreated fabric is immersed in a solvent B in which a reactive dye is dispersed for dyeing. After dyeing is completed, the dyed fabric is separated to obtain the dyed fabric. The reactive dye and the solvent B form a dyeing solution, and the solvent B includes a hydrogen bond donor and a hydrogen bond acceptor. The hydrogen bond donor is any one of lactic acid, urea, citric acid, and fructose. The hydrogen bond acceptor contains a carboxyl group that reacts with the ammonium group through amidation, and the mass ratio of the hydrogen bond donor to the hydrogen bond acceptor is 3 to 4:1.

[0009] In this case, both solvents A and B are composed of hydrogen bond acceptors and hydrogen bond donors in a specific molar ratio, offering advantages such as being green, biodegradable, highly soluble, low-cost, and recyclable. Solvent A is added during the pretreatment stage and subjected to microwave heating. The carboxyl groups in the hydrogen bond acceptors of solvent A react with the ammonium groups in cellulose via an amidation reaction, introducing quaternary ammonium groups. This modification process achieves anhydrous modification through an amidation reaction between the carboxyl groups in the hydrogen bond acceptors of solvent A and the ammonium groups in cellulose, increasing their affinity for dye molecules and the number of positive charges on the fiber surface. During dyeing, these increased affinity and positive charges, combined with the enhanced and promoted dye adsorption of solvent B by the fibers, impart a higher dye adsorption capacity to the fibers, thereby improving the fiber's dye uptake. Microwave heat treatment promotes and accelerates the amidation reaction between the carboxyl groups in the hydrogen bond acceptors of solvent A and the ammonium groups in cellulose, thereby increasing the dye uptake. This process is utilized for its short heating time, high efficiency, uniform heating, and rapid reaction. The quaternary ammonium salts generated in the above process also have excellent antibacterial properties. The reason is that the positively charged quaternary ammonium groups can adsorb negatively charged bacteria, causing the bacterial cell membrane to become thinner and rupture, the cell structure to be destroyed, and the leakage of internal cell substances, resulting in cell inactivation and achieving an antibacterial effect.

[0010] Furthermore, as a preference:

[0011] In step (1), the mass ratio of the fabric to be treated to solvent A is 1:4-10, and the soaking time is 4-6 hours. A mass ratio of the fabric to be treated to solvent A that is too low may result in incomplete modification, while a mass ratio that is too high increases the modification temperature and time, resulting in increased costs. The applicant's research has determined that a mass ratio of 1:4-10 is ideal for modification, and in particular, a mass ratio of 1:5 for the fabric to be treated to solvent A achieves a good compatibility between the modification effect and the modification cost.

[0012] In step (1), the microwave heating time is 5 to 25 seconds and the temperature is 100 to 200°C. More preferably, the microwave heating temperature is 100 to 120°C. The amidation reaction temperature between the ammonium group and the carboxyl group needs to be carried out above 80°C. In the reaction atmosphere provided in this scheme, 100 to 200°C is a more ideal reaction temperature range. Microwaves can use electromagnetic waves with a wavelength of 122 mm. The amidation reaction is affected by the heating time. If the heating time is too short, it will not promote the reaction between the carboxyl group in the solvent A and the ammonium group in the fabric. If the heating time is too long, the temperature will be too high, which will cause the betaine to decompose. Considering all factors, the radiation time of 5 to 25 seconds is most appropriate.

[0013] In step (1), after the pretreatment is completed, the pretreated fabric is obtained by centrifugation, and the solvent A is recovered at the same time, and the centrifugal speed is 2000-3000 rpm.

[0014] The effect is better when the hydrogen bond acceptor in solvent A has both carboxyl and quaternary ammonium functional groups.

[0015] As a preferred embodiment, the hydrogen bond acceptor of the solvent A is betaine (CAS: 590-47-6, molecular formula: C5H 11 NO2·H2O, molecular weight 135.16), betaine hydrochloride (CAS: 590-46-5, molecular formula: C5H 12 ClNO2, molecular weight 153.61). The modification effect is ideal when lactic acid is the hydrogen bond donor and betaine is the hydrogen bond acceptor.

[0016] In step (2), the dye bath ratio is 1:100-300, and the dyeing temperature is 50-80°C. The dye bath ratio is related to the dye uptake and fixation rate of the dye. Generally speaking, the dye uptake and fixation rate of the dye increase as the bath ratio decreases within a certain range. Under the dyeing environment provided by this scheme, the more suitable dye bath ratio is 1:100-300, and the optimal dye bath ratio is 1:100. The adsorption and dyeing properties of the dye are closely related to the temperature. As the temperature increases, the diffusion rate of the dye increases, which is conducive to the reaction between the fiber and the dye. However, too high a temperature will cause the dye to hydrolyze and reduce the fixation rate. In addition, the increase in temperature may cause the hydrogen bond receptor and ammonium group to continue to react during the dyeing stage. Under the dyeing environment provided by this scheme, the more suitable dyeing temperature is 50-80°C, and is optimal at 60°C. Reactive dyes such as 3BF red can be used.

[0017] In step (2), after dyeing is completed, the dyed fabric is obtained by centrifugation, and the solvent B is recovered at the same time, and the centrifugal speed is 2500-3000 rpm.

[0018] As a preferred embodiment, the hydrogen bond acceptor of the solvent B is any one of betaine, betaine hydrochloride, choline chloride, and L-carnitine. When the hydrogen bond donor is lactic acid and the hydrogen bond acceptor is choline chloride, the effect of promoting dye uptake is more ideal.

[0019] The fabric is any one of cotton fabric, linen fabric, wool fabric, silk fabric or a blend of two or more of cotton, linen, wool and silk.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) In the pretreatment stage, a reactive low-melting solvent A is used as a solvent and a reactant (i.e., the fabric to be treated) and the fabric to be treated is modified by microwave heating. The amidation reaction introduces quaternary ammonium groups to increase the positive charge on the fiber surface, thereby enhancing the affinity for dye molecules and improving the dyeing rate. In addition, the introduced quaternary ammonium groups can bind to bacteria and inactivate the bacteria, thereby enhancing the antibacterial effect of the fabric.

[0022] (2) During the dyeing stage, the fabric is dyed using a low eutectic solvent B as a dispersant for the dye. Solvent B has a strong hydrogen bonding ability. On the one hand, it can better disperse the dye, and on the other hand, it can facilitate the diffusion of the dye into the fabric, which helps to further improve the dyeing rate.

[0023] After the aforementioned treatment, the dyed fabric is dried and set to obtain the finished dyed product. Compared to the 60-65% dye uptake of traditional dyeing methods, this method achieves a dye uptake of over 95%. Furthermore, the dyeing process is water-free, resulting in color fastness of the fabric exceeding Grade 4, exceeding national standards for wear and use. Color accuracy of the fabric can reach over 80%, meeting color consistency standards. DETAILED DESCRIPTION

[0024] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below through specific embodiments.

[0025] In the following examples, silk fabric is used as the raw material fabric to illustrate the scheme.

[0026] Example 1

[0027] This example investigates the effect of adding solvent A during pretreatment on dye uptake. The specific process is as follows:

[0028] (1) Raw fabric 1 and raw fabric 2 were immersed in solvent A and water, respectively, and stirred to ensure full contact. The mass ratio of fabric to solvent (water) was 1:5, and the immersion time was 5 hours. Then, anhydrous modification pretreatment was performed by microwave heating, where microwaves were electromagnetic waves with a wavelength of 122 mm and a temperature of 120°C. After 15 seconds of modification treatment, the fabrics were separated by high-speed centrifugation at a rate of 2000 rpm to obtain pretreated fabric 1 and pretreated fabric 2, and solvent A was recovered at the same time. The hydrogen bond donor of solvent A was lactic acid, the hydrogen bond acceptor was betaine, and the mass ratio of hydrogen bond donor to hydrogen bond acceptor was 4:1.

[0029] (2) Pretreated fabric 1 and pretreated fabric 2 were immersed in solvent B for dyeing at a dye-bath ratio of 1:100 and a dyeing temperature of 60°C. 3BF red reactive dye was dispersed in solvent B at a concentration of 1 owf%. After dyeing for 80 minutes, the dyed fabrics were separated by high-speed centrifugation at a speed of 2500 rpm to obtain dyed fabric 1 and dyed fabric 2, and solvent B was recovered. The hydrogen bond donor in solvent B was lactic acid, the hydrogen bond acceptor was choline chloride, and the mass ratio of hydrogen bond donor to hydrogen bond acceptor was 4:1.

[0030] (3) The dyed fabric 1 and the dyed fabric 2 are dried and set (conventional drying and setting parameters can be used, such as: drying temperature 80°C, drying time 30 minutes; setting temperature 125°C, setting time 30 minutes), and finally the dyed finished product 1 and the dyed finished product 2 are obtained.

[0031] The dyeing effect of the finished dyed product 1 and the finished dyed product 2 was tested according to the following standards:

[0032] The dye uptake rate is calculated as follows:

[0033]

[0034] Among them, A0 is the absorbance of the original dye solution, A1 is the absorbance of the residual solution after dyeing, and each group of samples was measured three times to get the average value.

[0035] The color fastness test standards are: GB / T 3921-2008, GB / T 5711-1997, GB / T 3920-2008, GB / T3922-2013, GB / T 5713-2013.

[0036] The color accuracy test standard is: color accuracy above 80% is considered consistent.

[0037] Finished product 1 achieved a dye uptake of 97.13% and color fastness ratings greater than Grade 4, with both dry and wet rubbing color fastness reaching Grade 5. Its color fastness to soaping was Grade 4-5, and its color accuracy was 90.88%. Finished product 2 achieved a dye uptake of 78.86% and a color accuracy of 81.57%. Compared to the process without pretreatment, pretreatment with solvent A significantly improved dye uptake and color accuracy in finished product 1.

[0038] Example 1-1

[0039] The configuration of this embodiment is the same as that of embodiment 1, except that the raw fabrics are respectively soaked in solvent A shown in Table 1.

[0040] Table 1: Effect of different solvent A compositions on dye uptake

[0041]

[0042] The dyeing rate of the obtained finished dyeing product was tested (the method is the same as that of Example 1). By comparing Example 1 with Example 1-1, it can be seen that:

[0043] 1) Solvents A with different compositions have different dyeing effects (see numbers 1-5 in Table 1). Under the same mass ratio, the combination of lactic acid and betaine has the best dyeing effect, followed by the combination of lactic acid and betaine hydrochloride.

[0044] 2) When the components are the same but the proportions are different, the selected hydrogen bond acceptors and hydrogen bond donors show the same trend, that is, when the mass ratio of hydrogen bond donor to hydrogen bond donor is 3 to 4:1, the dyeing effect is better. Taking solvent A composed of lactic acid and betaine as an example, when the mass ratio of lactic acid: betaine is lower than 3:1 (see serial numbers 6-9 in Table 1), the solvent viscosity is high, resulting in a dyeing effect that is worse than that of Example 1; and when the mass ratio of lactic acid: betaine is higher than 4:1 (see serial numbers 12 and 13 in Table 1), there is a problem of incomplete modification due to the low betaine content in the solvent. The applicant conducted experiments on solvent A with other compositions, and all showed the same trend, which will not be recorded in detail here.

[0045] 3) Betaine and betaine hydrochloride both contain quaternary ammonium and carboxyl groups in the hydrogen bond acceptor, while choline chloride does not. Compared with the use of solvent A (No. 14 in Table 1) in the modification pretreatment stage, the dyeing process using solvent A containing carboxyl groups (Nos. 4 and 5 in Table 1) achieved higher dye uptake.

[0046] Example 2

[0047] This example investigates the effect of the heating method on the dye uptake during pretreatment. The specific process is as follows:

[0048] Raw fabrics 3 and 4 were immersed in solvent A (lactic acid as the hydrogen bond donor, betaine as the hydrogen bond acceptor, with a mass ratio of 4:1). Stirring was performed to ensure thorough contact, with a mass ratio of 1:5 between the raw fabric and solvent A. The immersion time was 5 hours. The fabrics were then subjected to anhydrous modification pretreatment using microwave heating and oven heating, respectively. After pretreatment, the fabrics were separated by high-speed centrifugation at 2000 rpm to obtain pretreated fabric 3 and treated fabric 4, and solvent A was recovered.

[0049] Microwave heating parameter settings: microwave is an electromagnetic wave with a wavelength of 122 mm, a temperature of 120 °C, and a modification time of 15 s.

[0050] Oven heating parameter settings: temperature 120℃, duration 15min.

[0051] (2) Pretreated fabric 3 and pretreated fabric 4 were immersed in solvent B (lactic acid as hydrogen bond donor, choline chloride as hydrogen bond acceptor, and a mass ratio of hydrogen bond donor to hydrogen bond acceptor of 4:1) for dyeing at a dye bath ratio of 1:100 and a dyeing temperature of 60°C. 3BF red reactive dye was dispersed in solvent B, and the concentration of 3BF red reactive dye was 1 owf%. After dyeing for 80 minutes, the fabrics were separated by high-speed centrifugation at a speed of 2500 rpm to obtain dyed fabric 3 and dyed fabric 4, and solvent B was recovered.

[0052] (3) The dyed fabric is dried and shaped (the drying and shaping parameters are the same as those in Example 1), and finally dyed finished products 3 and 4 are obtained.

[0053] The dyeing effects of the finished dyed products 3 and 4 were tested (the method was the same as that in Example 1). The results showed that the dyeing rate of the finished dyed product 3 corresponding to the process was 97.13%, the color accuracy was 90.88%, and the color fastness was above level 4; the dyeing rate of the finished dyed product 4 corresponding to the process was 85.77%, the color accuracy was 81.46%, and the color fastness was above level 4. Compared with using oven heating as a pretreatment condition, microwave heating pretreatment can achieve better dyeing effect in a shorter time.

[0054] In this case, we also experimented with the pretreatment time and found that the dyeing effect achieved by microwave heating for 5 seconds was higher than that achieved by oven heating for 5 minutes. Continuing to extend the microwave treatment time to 10 seconds, 15 seconds, 20 seconds, and 25 seconds, the dyeing effect was still higher than that achieved by oven heating for 10 minutes, 15 minutes, 20 minutes, and 25 minutes.

[0055] Example 3

[0056] This example investigates the effect of solvent B on dye uptake during the dyeing stage. The specific process is as follows:

[0057] (1) Raw fabric 5 and raw fabric 6 were soaked in solvent A (lactic acid as hydrogen bond donor, betaine as hydrogen bond acceptor, and the mass ratio of hydrogen bond donor to hydrogen bond acceptor was 4:1), stirred to ensure full contact, and the mass ratio of raw fabric to solvent A was 1:5. The soaking time was 5 h. Then, anhydrous modification pretreatment was performed by microwave heating, wherein microwaves were electromagnetic waves with a wavelength of 122 mm, a temperature of 120°C, and a modification time of 15 s. After the reaction was completed, the pretreated fabrics 5 and 6 were obtained by high-speed centrifugation at a rate of 2000 rpm, and solvent A was recovered at the same time.

[0058] (2) Pretreated fabric 5 and pretreated fabric 6 were immersed in solvent B (lactic acid as hydrogen bond donor, choline chloride as hydrogen bond acceptor, and a mass ratio of hydrogen bond donor to hydrogen bond acceptor of 4:1) and water, respectively, for dyeing. The dye bath ratio was 1:100, the dyeing temperature was 60°C, and 3BF red reactive dye was dispersed in solvent B and water. The concentration of 3BF red reactive dye was 1 owf%. After dyeing for 80 minutes, the solvent B and water were removed by high-speed centrifugation at a speed of 2500 rpm to obtain dyed fabric 5 and dyed fabric 6.

[0059] (3) The dyed fabric is dried and shaped (the drying and shaping parameters are the same as those in Example 1), and finally dyed finished products 5 and 6 are obtained.

[0060] The dyeing rate of the finished dyeing product 5 and the finished dyeing product 6 was tested (the method was the same as in Example 1). The results showed that the dyeing rate of the finished dyeing product 5 corresponding to the process was 97.13%, the color accuracy was 90.88%, and the color fastness was level 4 or above; the dyeing rate of the finished dyeing product 6 corresponding to the process was 80.19%, the color accuracy was 82.08%, and the color fastness was level 4 or above; compared with the finished dyeing product 6 in which no solvent was added during the dyeing stage, the dyeing rate of the finished dyeing product 5 in which solvent B was added was significantly improved.

[0061] The applicant also conducted experiments on the composition of solvent B, which showed a similar influence trend as the composition of solvent A, and will not be described in detail here.

[0062] Example 4

[0063] In this example, the dyed finished product 1 prepared in Example 1 was used as a sample, and the antibacterial rate of the silk fabric sample against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was tested according to the improved AATCC100-1999 method. The specific process is as follows:

[0064] (1) The dyed finished product 1 prepared in Example 1 was cut into 1.5 cm×1.5 cm square samples, and then the samples were sterilized under ultraviolet light for 30 minutes.

[0065] (2) Add 20 μL of standard bacterial solution to the sample and incubate for 1 h.

[0066] (3) Take out the sample and place it in a test tube containing 5 mL of PBS buffer solution, and shake it in a constant temperature incubator for 10 minutes.

[0067] (4) Finally, 100 μL of PBS solution was applied to the LB agar plate and incubated at 37°C for 24 h. The antibacterial properties of the modified dyed fabric were evaluated by calculating the antibacterial rate. The antibacterial rate (BR) was calculated according to the following formula:

[0068]

[0069] Where A and B are the number of bacterial colonies in the solid culture medium after the antibacterial rate test of the silk fabric sample and the original silk fabric, respectively. Each group of samples was tested three times and the average value was obtained.

[0070] The antibacterial performance results are as follows:

[0071] The fabric obtained by the dyeing method provided in this case has obvious antibacterial effect on Escherichia coli and Staphylococcus aureus, with an antibacterial rate of 99.83%.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

[0073] Comparative Example 1

[0074] CN112813708A was used as a comparative example (based on Example 1 thereof), and its dyeing process and dyeing effect were compared with Example 1 of this case. The results are as follows:

[0075] Table 2: Dyeing effect comparison table of Example 1 and Comparative Example 1

[0076]

[0077] From the comparison of Table 2, it can be seen that: for the same red reactive dyeing of silk fabrics, this case has the obvious advantages of simple dyeing process, short dyeing cycle, high dye uptake, high antibacterial property and low wastewater volume.

Claims

1. A fabric dyeing method, characterized in that, The following steps are involved: (1) Pretreatment: After the fabric to be treated is fully soaked in solvent A, microwave heating is performed for water-free modification pretreatment to obtain pretreated fabric. The fabric to be treated is made of an ammonium-containing material, The composition of the solvent A is lactic acid and betaine = 3-4:1, mass ratio; (2) Dyeing: The pretreated fabric is immersed in dye solution to obtain dyed fabric. The dye liquor contains reactive dyes and solvent B, The composition of the solvent B is lactic acid:choline chloride=4:1, mass ratio.

2. A fabric dyeing method according to claim 1, characterized in that: In step (1), the mass ratio of the fabric to be treated to solvent A is 1:4-10, and the soaking time is 4-6 h.

3. A fabric dyeing method according to claim 1, characterized in that: In step (1), the microwave heating time is 5 to 25 s and the temperature is 100 to 200 °C.

4. A fabric dyeing method according to claim 3, characterized in that: The microwave heating temperature is 100-120°C.

5. A fabric dyeing method according to claim 1, characterized in that: In step (1), after the pretreatment is completed, the pretreated fabric is obtained by centrifugation, and the solvent A is recovered at the same time, and the centrifugal speed is 2000-3000 rpm.

6. A fabric dyeing method according to claim 1, characterized in that: In step (2), the dyeing bath ratio is 1:100-300, and the dyeing temperature is 50-80°C.

7. A fabric dyeing method according to claim 1, characterized in that: In step (2), after dyeing is completed, the dyed fabric is obtained by centrifugation, and the solvent B is recovered at the same time, and the centrifugal speed is 2500 to 3000 rpm.

8. A fabric dyeing method according to claim 1, characterized in that: The fabric is any one of cotton fabric, linen fabric, wool fabric and silk fabric, or a blended fabric of two or more fibers of cotton, linen, wool and silk.

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